b – Select to Save as BMP
g – Select to Save as GIF
i – Select to Save as IFF
j – Select to Save as JPEG
p – Select to Save as PNG
s – Save image(s)
a – Save image or a batch of images under a new name/prefix. In batch-image
mode you also enter the start incremental value of the batch.
m – Add comment to the image(s)
r – Opens the Image Resize window
z – Toggle re-size on and off

n -If installed, open the URL in NetSurf
w – If installed, open the URL in OWB
t – If installed, open the URL in Timberwolf (option currently disabled til TW gets a command line)
d – Download the given URL to the current directory
u – Use the currently selected option

Slideshow Mode

p/backspace – Go to parent directory
e – Open selected image in editor
Arrows keys to move around, HOME and END to jump to the beginning or the end of
the slideshow.
+ and – To Zoom in-and-out of the image

The mouse wheel is also supported for Zooming in-and-out of the image.